Gas testing device



Oct. 11, 1949. H. A. WINTERMUTE 2,434,202

GAS TESTING DEVICE Filed July 29, 1946 2 Sheets-Sheet 1 Ella-=1 Oct. 11,1949.

Filed July 29, 1946 2 SheetsSheet 2 Line Fan motor 3/ .33 Timer motor 42Damper motor Speed reducer Dumper closed lseconosl E :L r=;

6 I20 second cycle 96 58:. He 6 2 sec. sec 28 sec. 16sec. l4 secv 32sec. 20 sec. 2:

2 Q) wc 5 f) O 8 E t0 3 a E m 0 3 2 as a a o a 5 g a L E as 9 *5 Q a) oo E E2 2 E O a: 3 0 g 5 o O 3 :5 Q a E g r 5 Q PGHOd of full Period ofdying Per|od of purgmq & corona dlSCh. away of corona dlsch replenishingof on I grwcvrvfm Patented Oct. 11, 1949 GAS TESTING DEVICE Harry A.Wintermute, Plainfield, N. J assignor to Research Corporation, New York,N. Y., a corporation of New York Application July 29, 1946, Serial No.686,974

'7 Claims.

This invention relates to a testing device and more particularly to adevice for obtaining a test precipitate or deposit of suspended matterfrom a determinable sample of gas.

The device of the invention finds particular application in the testingof air to determine the natur and amounts of material suspended therein,but is suitable for the testing of other gases as well.

Objects of the invention are to provide an im-- proved device of thetype in question utilizing principles of electrical precipitation tocollect a precipitate of suspended matter from a sample of air; toprovide a fully automatic testing device in the use of which the size ofgas sample treated may be determined with a high degree of accuracy; toprovide a testing device wherein a high percentage or substantially allof the suspended matter is precipitated from the gas sample; to provide,in such a device, means whereby a precipitate-collecting mat may beconveniently placed in and removed from the device; and to provide inthe device simple and effective timecontrolled means for its automaticoperation.

It is also an object of the invention to provide a superior andefficient process for obtaining a test precipitate of suspended matterfrom an accurately determined sample of air or other gas.

Another object is to provide a device for obtaining a test deposit upona collecting mat whereby examination and appraisal of the deposit isfacilitated. The collecting mats upon which the device of the inventionis adapted to deposit suspended matter can be readily removed from thedevice in condition for weighing and microscopic examination orculturing, if biotic in nature.

In a typical embodiment, the invention takes the form of a device forobtaining a test precipitate of suspended matter from a determinablesample of gas including an electrical precipitator having complementaryelectrodes defining a precipitating zone therebetween, means forestablishing a succession of stationary gas samples in the precipitatingzone, and means for impressing an electric potential between theelectrodes when the gas samples are in the precipitating zone. Theelectrical precipitator incorporated in the device specificall takes theform of a single-stage precipitator having a single pair ofcomplementary electrodes, the extended surface electrode of thecomplementary pair being provided by the walls of the precipitatorhousing. Means is also provided permitting ready access to the interiorof the precipitator for the 2 introduction and removal of aprecipitate-collecting mat.

The means for establishing a succession of stationary gas samples in theprecipitator preferably includes a continuously-acting gas suctiondevice or aspirator normally tending to draw a stream of gas through theprecipitating zone and a damper arranged to be intermittently opened andclosed to permit periodic purging of th precipitating zone andreplacement of the gas sample from which suspended matter has been pre-'cipitated with a fresh sample.

There is also preferably provided in the device of the invention meansinterconnected with the means for establishing the succession ofstationary gas samples for actuating the electric potential impressingmeans only when discrete gas samples are at rest in the precipitatingzone.

In its method aspects, the invention includes a process for obtaining atest precipitate of suspended matter from a determinable sample of gaswhich comprises establishing a succession of stationary gas samples in aprecipitating zone and establishing an electric precipitating field insaid precipitating zone when said samples are in said zone.

For the purpose of more particularly pointing out the principles of theinvention, reference is made to the accompanying drawing showing anembodiment of the invention and to the following detailed descriptionthereof. In the drawi Fig. 1 is a semi-diagrammatic plan view of atesting device in accordance with the invention;

Fig. 2 is a vertical sectional view taken along the line 22 of Fig. 1;

Fig. 3 is a circuit diagram; and

Fig. 4 is a chart showing a typical cycle of operation.

Referring particularly to Figs. 1 and 2 of the drawing, the testingdevice shown includes an electrical precipitator It, a power pack I:providing high tension current for the complementar electrodes of theprecipitator, an aspirating device I2, a damper operating motor I3, a.timer I4, and suitable electrical conductors, all to be more fullydescribed hereinafter.

The electrical precipitator H] has a base I4 of box-like constructionhaving a circular opening I5 at the top. A flanged receptacle I6 ismounted upon the top of the base around the opening I5 to provide forthe reception of a cylindrical element I! which serves not only as apart of the precipitator casing but also as an extended surfacelectrode. The cylinder H is open at the bottom and its bottom edgerests upon a ledge iii, the ledge being a portion of the top of the baseH1 projecting inwardly of the flanged receptacle 56. An annular disc is?is affixed to the top of the cylinder, the opening '23 of the discgiving access to the interior of the precipitator.

Mounted centrally of the base upon an insulator 2i. and projectingaxially into the cylinder ii is a discharge electrode 22 having afine-Wire tip or dis ge point center of the dis- "t is located atapproximately the cenn-der to provide relativelyuniform corona discargeand precipitating field.

The pack H is of conventional design and provides a source of highpotential current for application to the complementary electrodes l1 and22 defining the precipitating zone. Although not shown in Figs. 1 and 2,the high tension output terminals 2 and 25 of the power pack areconnected through appropriate leads to the base i of the precipitatorand the discharge electrode respectively, as indicated in the circuitdiagram of Fig. 3.

An open cylindrical precipitate-collecting mat 26, upon which suspendedmatter is precipitated, may be inserted in the cylinder l! duringoperation of the device. It fits snugly within the cylinder i? and iseasily inserted into and removed from the cylinder which may bedetachedfrom its receptacle for this purpose. The mat may be formed froma length of sheet celluloid, paper or other sheet material rolled intocylindrical configuration or it may be molded as an unbroken cylinderfrom plastic material or otherwise suitably formed.

A gas conduit 2'! leads from the base ltof the precipitator to theexhaust tube 28 of the suction device 2. The exhaust tube may be formedfrom a length of pipe of square cross section reduced to circular crosssection at 30. It is open at both ends, and into the left end projectsthe shaft 3| carrying an exhaust fan 32, the shaft and fan being drivenby the motor 33.

A damper is fixed to a vertical shaft 35 journalled at top and bottom inbearings formed in the pipe 523 in such manner that the damper may beswung to uncover and re-cover the end of conduit 2'? by rotating theshaft 35 for the purpose of purging and replenishing gas in theprecipitating zone. In its fully open position, the damper effectivelyblocks the right-hand end of the e" aust tube 25, thus applying the fullsuction ct of the fan to the precipitator. Conversely, when the damperis fully closed the right-hand end of the tube 28 is open to atmosphereallowing free flow of air through the tube and relieving to a largeextent gas pressure difierential across the damper and minimizing thetendency for gas to be exhausted from the precipitator. An arm 36 isfixed to the top of shaft 35 and the outer end of the arm is connectedby a link 3? to the arm 36 of the damper operating motor l3. A tensionspring 39, fixed at one end to the arm 33 and at the other end to thehousing of motor it, normally urges the damper 34 to closed position. Itwill be seen that counterclockwise movement of the arm 38 swings thedamper to open position.

The timer id, as will be explained more fully hereinafter, isconstructed and arranged to time the opening and closing of the damperand the energization of the power pack in accordance with a preselectedcycle of operation.

A typical cycle of operation is illustrated by this last mentionedperiod, the damper operating fio-i obtained only from relatively largeair volumes.

-ment to extended precipitation conditions and to 4 the chart of Fig. 4.The cycle is of seconds duration and includes a precipitation periodduring which a quiescent, discrete sample of gas is treated in theprecipitation zone to deposit such particulate matter as may besuspended in the sample, and a period during which the precipitatingzone is purged of the treated sample and a fresh sample of gas to betreated is introduced into the precipitating zone.

In the chart of Fig. 4, the legends on the vertical lines state theposition of the damper or whether the power pack is on or on. Time isindicated as running from left to right, total elapsed time being shownin the top line of figures and time intervals between. vertical linesbeing shown in the second line of figures. The legends on the bottomlines of the chart designate the several periods of the cycle.

The cycle has an initial six second period in which the damper is closedand a fresh sample of gas is at rest in the precipitating zone. At'theend of six seconds th power pack is turned on and remains on fortwenty-eight seconds for a period of full corona discharge, after whichtime the power pack is deenergized. Due to the characteristics of thepower pack and its association with the precipitator, corona dischargedoes not cease immediately, but slowly dies away over a period of thirtyseconds. About half way through motor starts; the damper begins to openat the end of this period. The damper is fully open thirty-two secondsafter it starts to open; it starts to close in another twenty secondsand is fully closed in an additional four seconds. Thus it will be seenthat the period of purging and replenishing of air extends for a periodof fiftysix seconds at the end of the cycle.

From the foregoing description of a typical cycle it will be seen that adiscrete gas sample is subjected to corona discharge only while it is atrest in the precipitating zone and that no precipitation occurs duringpurging and replenishment of the gas sample. Since the volume of theprecipitating zone can be accurately measured or calibrated, the volumeof gas sample treated in one cycle is substantially exactly known andthe total volume of gas treated in a plurality of successive cycles canbe calculated with a high degree of accuracy.

As will be understood by those skilled in the art, the pollution ofordinary air is measured in parts per million of air and consequently,ap-- preciable deposits of particulate matter can be Since it isdesirable to obtain the deposit on a small area of test mat tofacilitate weighing and examination, samplers of correspondingly smallvolume must be run for periods measured in hours or even days to obtain.an adequate deposit. The device of the present invention, owing to itsability to precipitate substantially all of the particulate matter fromeach discrete increment of the total gas sample by subjecting theincrethe accuracy with which the total volume of gas sample can beascertained, provides a very reliable test device.

An exemplary circuit diagram is shown in Fig. As will be understood fromthe figure, the fan motor 33 runs continuously creating a constantsuction in the aspirating device l2. The

timer motor 33a also runs continuously, making and breaking the contacts68 in conventional manner to energize and deenergize the power pack H atthe desired times. The timer mot-or similarly actuates the contacts 4!to energize and deenergize the damper motor 13 at the desired times in:the cycle of operation. A conventional speed reducer 42 driven by thetimer motor 33a drives cams 43 and 44. Cam 43 actuates the contacts 40to energize and deenergize the power pack II and cam 44 actuates thecontacts 4| to energize the damper motor in accordance with the selectedoperating cycle. It will be understood that a conventional drivemechanism, including suitably designed cams, is included in the dampermotor housing to actuate the arm 38 to open and close the damper 34 inaccordance with the requirements of the selected operating cycle.

The apparatus can be widely applied. In addition to dusts and othersuspended solids commonly met with, mists of low vapor pressure liquidscan be collected and weighed, and otherwise observed. And, where bioticspecimens such as molds and bacteria are to be collected for study, theprecipitate-collecting mat can be coated with a medium that will permitsubsequent culturing. Tests have proven that the electric discharge usedis not lethal to such organisms.

I claim:

1. A device for obtaining a test precipitate of suspended matter fromgas which comprises an electrical precipitator including a casingdefining a precipitating chamber, the walls of said casing providing anextended surface electrode structure, complementary discharge electrodemeans positioned in said precipitating chamber, means for impressing anelectric potential across said electrodes, gas inlet means opening intosaid precipitating chamber, opposed gas outlet means for removal of gasfrom said precipitating chamber, continuously acting gas suction meansconnected to said gas outlet means, a damper for controlling the flow ofas from said gas outlet means to said gas suction means, time-controlledmeans for intermittently opening and closing said damper to establish asuccession of stationary gas samples in said precipitating chamber and.for energizing said electric potential impressing means only when saidgas samples are in said chamber, and means for positioning aprecipitatecollecting mat in said precipitating chamber adjacent to thewalls of said casing.

2. A device for obtaining a test precipitate of suspended matter fromgas which comprises an electrical precipitator having complementaryextended surface and discharge electrodes defining a precipitatingchamber therebetween, means for passing a stream of gas through saidprecipitating chamber, valve means for interrupting flow of gas throughsaid precipitating chamber, and means including a timing device foroperating said valve means and for energizing said complementaryelectrodes only when said valve means is in closed position to establisha stationary gas sample in said precipitating chamber.

3. A device for obtaining a test precipitate of suspended matter fromgas which comprises an electrical precipitator having complementaryextended surface and discharge electrodes defining a precipitatingchamber therebetween, means for passing a stream of gas through saidprecipitating chamber, valve means for interrupting flow of gas throughsaid precipitating chamber, and means for cyclically opening and closingsaid valve means and energizing said complementary electrodes only whensaid valve means is in closed position to establish a stationary gassample in said precipitating chamber.

4. A device for obtaining a test precipitate of suspended matter fromgas which comprises an electrical precipitator having complementaryextended surface and discharge electrodes defining a precipitatingchamber therebetween, means for passing a stream of gas through saidprecipitating chamber, valve means for interrupting flow of gas throughsaid precipitating chamber, and means actuated by said valve means forenergizing said complementary electrodes only when said valve means isin closed position to establish a stationary gas sample in saidprecipitating chamher.

5. A device for obtaining a test precipitate of suspended matter fromgas which comprises an electrical precipitator having complementaryextended surface and discharge electrodes defining a precipitatingchamber therebetween, means for positioning a precipitate-collecting matadjacent to said extended surface electrode, means for passing a streamof gas through said precipitating chamber, valve means for interruptingflow of gas through said precipitating chamber, and means for cyclicallyopening and closing said valve means and energizing said complementaryelectrodes only when said valve means is in closed position to establisha stationary gas sample in said precipitatin chamber.

6. A device for obtaining a test precipitate of suspended matter fromgas which comprises an electrical precipitator having complementaryextended surface and discharge electrodes defining a precipitatingchamber therebetween, means for passing a stream of gas through saidprecipitating chamber, valve means for interrupting flow of gas throughsaid precipitating chamber, and time-controlled means for successivelyand cyclically closing said valve means to establish a stationary gassample in said precipitating chamber, energizing said complementaryelectrodes, de-energizing said complementary electrodes and opening saidvalve means.

7. A device for obtaining a test precipitate of suspended matter fromgas which comprises an electrical precipitator having complementaryextended surface and discharge electrodes defining a precipitatingchamber therebetween, means for positioning a precipitate-collecting matadjacent to said extended surface electrode, gas inlet and gas outletmeans communicating with said precipitating chamber, a continuouslyacting fan for causing a stream of gas to be tested to flow through saidprecipitatin chamber, a damper for interrupting flow of gas through saidprecipitating chamber, and time-controlled means for successively andcyclically closing said damper to interrupt flow of gas through saidprecipitating chamber, energizing said complementary electrodes,de-energizing said complementary electrodes and opening said damper tore-establish flow of gas through said precipitating chamber.

HARRY A. WINTERMUTE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,096,765 Strong May 12, 19141,779,569 Thompson Oct. 28, 1930 2,307,602 Penney et a1 Jan. 5, 1943

